Pre-electrosensitive printing plate and novel methods of electro-defining images



PRE-ELECTRQBENSITIVE PRIIN'IING PLATE AND NOVEL METHODS OF ELECTRO-DEFINING IMAGES Filed Oct. 12, 1963 Dec. 19, 1967 J J. I'TO 3,359,

INVENTOR.

,JAc-KJ /70 WW *W United States Patent PRE-ELECTROSENSITIVE PRINTING PLATE AND NOVEL METHODS OF ELECTRO-DE- FINING IMAGES Jack J. Ito, Roseville, Minn., assignor to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Oct. 12, 1963, Ser. No. 317,450 8 Claims. (Cl. 96--1) ABSTRACT OF THE DISCLOSURE A lithographic printing plate and method of imaging the same through electrophoresis. The plate is pro-electrosensitive in that it carries its own electrosensitive image-forming material as an integral pre-coating associated with a metal backing element. The image-forming coating is made up of or includes an electrophoretically responsive and electrophoretically-orientable material of discrete mobile molecules (such as disodium dodecyl diphenyl ether disulfonate) having an anionic moiety and an organophilic portion. When subjected to an electromotive force in a conductive medium (with the backing connected as the anode), the molecules move and become stably oriented in the areas of current flow, with the anionic moiety pointed toward the anode and the organophilic portion away therefrom to present the organophilic ink-receptive surface. Where the electrophoretically responsive material contains a tough filmforming organophilic resin, e.g. polyvinyl acetate, the resin becomes firmly bonded in the areas of current flow, while being readily wiped away in areas not subjected to current flow.

The present invention relates to a novel pre-electrosensitive printing plate, on which an image is anodically generated or defined from self-contained constituents, and more broadly to methods or procedures for forming useful images from initially orientable electrophoretically responsive materials on anodic substrates. More specifically my invention especially concerns a pre-electrosensitive lithographic plate which, when anodically subjected to the electromotive forces in selected areas corresponding with a desired image, has generated or defined on the surface thereof firmly bonded water-insoluble oleophilic (ink receptive) areas corresponding with said image.

Photolithography has been well known, and in wide commercial use, for more than forty years. More recent- 1y, since about 1950, presensitized metal lithographic plates have been commercially available: see Jewett and Case Patent No. 2,714,066, granted July 26, 1955, based on application filed Dec. 6, 1950. Such presensitized metal lithographic plates are shipped and stored in lightproof containers in the light-sensitive condition, and ex posed and used as desired weeks or months after manufacture. The provision of the presensitized metal lithographic plate afiected commercial lithography in the early 1950s, much as the provision of presensitized photographic film affected the retail photography industry many years earlier.

While the light-sensitivity of ordinary photographic film has increased substantially over the years, so that now an ordinary photographic film can be exposed in a fraction of a second even under rather unfavorable light conditions, photolithographic plates, even today, conventionally require an exposure time of several minutes, while still utilizing high intensity light sources.

On the other hand, photo-techniques have constituted substantially the only practical way of lithographically producing faithful copies of originals having complex Patented Dec. 19, 1967 images. Thus, while highly successful printing is still accomplished by photolithographic techniques, there nonetheless has been a need long existing for lithographic plates on which complex images, such as half tone images, can be formed and made ready for the press quickly and easily and without need of intense and prolonged exposure.

More recently, the need for such a plate has been intensified in conjunction with increased utilization of data storage and retrieval, such as storage of information, e.g. drawings and other documents, on microfilm. This science of information storage and retrieval has received much attention over the last decade or so. Numerous systems are commercially available by which documents can be stored on microfilm and quickly retrieved and made available in condition for viewing. Some such systems include means for quickly obtaining a very limited number of copies of desired microfilmed documents: see Johnson et al. Patents Nos. 3,010,883 and 3,010,884, granted Nov. 28, 1961, and No. 3,011,- 963, granted Dec. 5, 1961.

Where more than a few copies of a microfilmed document are required, duplication lithographically on small and relatively inexpensive ofiice lithographic presses has seemed ideal. But, until quite recently, the relatively long time it has taken to expose and develop a photolithographic plate has retarded utilization of lithographic reproduction in the field, and the use of microfilm data storage for live files has correspondingly been retarded.

One example where lithographic retrieval of microfilm stored information is especially desirable is engineering reproduction, i.e. reproduction of engineering drawings stored on the microfilm. This eliminates need for storing bulky original drawings. Further, the lithographic reproduction of forms, bulletins, circulars, price lists, etc. by industrial in plant printing shops would be made much less expensive by simplified, fast preparation of plates from material stored on microfilm, microfilm storage having the added advantage of eliminating storage of processed lithographic plates, full size negatives, and original art. 1

While others have directed their attention to the provision of lithographic plates as a supplemental tool to data storage and retrieval, and there has been recent commercial activity in this regard, there nonetheless long has been a need and more recently an intensified need for the provision of a lithographic plate embodied in practical commercial form which is quickly, simply and inexpensively made, and which is pre-electrosensitive, i.e. carries the image-forming material as an integral component thereof (much as the prephotosensitive coating on a presensitized photo-lithographic plate forms an integral component thereof). Insofar as I am aware, no one has provided such a tool.

In accordance with the present invention, a lithographic plate, ready for the press, can be made directly from microfilm, simply and inexpensively, in a fraction of a minute. Briefly, this is accomplished by projecting an enlargement of a retrieved microfilm frame onto a photoconductive sheet, i.e., a sheet which is normally non-conductive but which in areas exposed to light becomes conductive. This well-known step is accomplished in a matter of a few seconds, for example, in about ten seconds or less. The sheet containing the enlarged photoconductive image is then brought into conductive contact with the preelectrosensitive plate of the present invention, in the presence of an electrically conductive liquid (such as water or a mixture of water and ethylene glycol) and briefly, e.g. for about a second or less, subjected to an electric potential of a few volts, the photoconductive sheet serving as the cathode and my plate I 3 serving as the anode. An organophilic ink-receptive image is generated and defined on the surface of the plate, the background or non-image areas being hydrophilic. Without further treatment the plate is ready for the press.

My novel structure, and the procedure employed in connection with the use thereof Will be described in somewhat more detail with the aid of the accompanying drawing, in which FIGURE 1 shows in enlarged and diagrammatic form, a broken away view of a preferred form of the present invention;

FIGURE 2 shows the plate of FIGURE 1 after generation of the ink-receptive image, and

FIGURE 3 shows a schematic view, illustrating suitable apparatus and procedure, in connection with my invention.

Referring now to the drawing, and especially to FIG- URES 1 and 2, the plate comprises an aluminum foil laminated and bonded to a high wet-strength natural kraft paper 11. The aluminum is provided with a very thin hydrophilic silicate treatment 12 on its exterior surface. Over and in contact with the hydrophilic surface of the aluminum, and in conductive relation With the aluminum (the silicate treatment will pass a current), is a coating 13 of an electrophoretically responsive and electrophoretically orientable material which may (and preferably does) contain a tough organophilic resin material. Upon subjecting the plate to an electric potential, with the plate serving as the anode, the electrophoretically responsive material becomes oriented and firmly bonded in the areas 13a (FIGURE 2) through which current passes. The areas 13a, which are image areas, are organophilic and ink-receptive in character.

With reference to FIGURE 3, which illustrates a process (as might be carried out in a unitary apparatus), roll contains a supply of a photoconductive sheet material 21. Said sheet material 21 passes in the image plane of a microfilm projector 22, which projects the contents of a microfilm frame, enlarged to suitable size according to the size of lithographic reproduction desired, where the sheet material 21 is briefly exposed on the light-sensitive surface. The exposed sheet is then passed through a dip tank containing an appropriate conductive liquid 23 such as an ethylene glycol-water solution. The thus wet sheet is then passed between squeeze rolls 24, and into intimate contact with (exposed side against), the coated surface of the preelectrosensitive sheet material 25, described above, which has been withdrawn from stock roll 26 and also passed between the squeeze rolls.

The two stock rolls 20 and 26 are connected to a source of electric power, for example, a 20 volt 60-cycle alternating current source, such that the photoconductive sheet material 21 and the aluminum foil of the lithographic sheet 25, are connected into circuit. The conductive liquid 23 insures good conductive contact between the conductive areas of the sheet 21 and the electrophoretically responsive coating 13 (FIGURE 1) of the lithographic sheet 25.

A current passage for less than one second is suflicient to cause the electrophoretically responsive and electrophoretically orientable coating on the lithographic sheet to become firmly bonded to the hydrophilic aluminum base in the areas where current passes, i.e. in the areas corresponding to the image of the microfilm original, whereby the image is generated and defined on the plate.

Thereafter, the spent photoconductive sheet 21 is wound upon discard roll 27. The lithographic image-containing sheet is then cut to suitable plate size, whereupon it is ready for the press.

In describing the present invention, I am aware that photoconductive sheets have been known for more than two decades, and that such materials have been advocated as being useful, in one way or another, in connection with lithographic reproduction. For example, see Carlson Patent No. 2,297,691, granted Oct. 6, 1942, on application filed Apr. 4, 1939, and in particular page 4, column 4 2 thereof. I am also aware that metal substrates have been coated with resinous materials from emulsions, and electrophoretically. See Clayton Patent No. 2,215,143, granted Sept. 17, 1940, on application based on a date of July 6, 1935. Lacquers or waxy materials have also been applied as composite coatings on metal substrates utilizing electric currents to cause or assist in the deposition, as disclosed, for example, in Sumner Patent No. 2,215,167, granted Sept. 17, 1940, on application based on a date of Mar. 30, 1937. Emulsions disclosed in the Sumner patent are stabilized with an emulsifying agent in the aqueous phase, for example, rosin soap.

Notwithstanding this and other prior art such as is referred to hereinabove, insofar as I am aware, even though suitable equipment and materials have been long available, he one prior to the present invention has provided a printing plate having firmly bonded organophilic image areas generated thereon from an electrophoretically responsive material. Nor has anyone provided, to my knowledge, a commercially useful pre-electrosensitive lithographic plate. Nor, insofar as I am aware, has the art appreciated the many and varied uses and advantages inhering in the generation of an image on a substrate, by the methods and techniques described herein.

Having now described my invention in a general way, the same will now be specifically illustrated in connection with the following non-limiting examples.

Example I An aluminum foil having a thickness of about onehalf mil and laminated to a 65-pound high wet-strength natural kraft paper was first treated with aqueous sodium silicate solution as described in Jewett and Case Patent 2,714,066, granted July 26, 1955, to impart a permanently hydrophilic surface on the aluminum, following which the treated aluminum surface was washed to remove excess water-soluble alkali material. A polyvinyl acetate water emulsion (Elvacet 81-900 marketed by the Du Pont Company), 55% solids by weight, was stirred together with disodium dodecyl diphenyl ether disulfonate (Benax 2A1 marketed by Dow Chemical Company), 45% solids by weight, in a ratio of 1:1 by volume. Thus the weight ratio of polyvinyl acetate to disodium dodecyl diphenyl ether disulfonate was approximately 55:45. The mixture was then coated onto the silicate treated surface of the treated aluminum paper laminate to a dry coating weight of 10-20 milligrams per square foot. The resultant plate size was 10 inches by 15 inches.

A dye-sensitized zinc oxide photoconductive sheet, prepared as described in Example I of Johnson et al. US. Patent No. 3,010,884, granted Nov. 28, 1961, and further provided with a hydrophilic colloidal silica coating on the light-sensitive surface, was projection exposed (enlargement 15X) for about ten seconds through a microfilm negative of an engineering line drawing. The composite photoconductive sheet employed is manufactured and sold by 3M Company, St. Paul, Minn., as Thermo- Fax brand Filmac reader printer copy paper. Exposure time and light-intensity at the image plane (image 10 x 11") were such to yield maximum exposure through the transparent areas of the negative without burning through the opaque areas of the negative.

The exposed photoconductive sheet was then wet with an ethylene glycol-water solution (1:1 by volume), following which it and the aluminum plate were rolled into intimate contact with the wet light-exposed surface of the photoconductive sheet and the coated surface of the aluminum plate facing and in contact. An alternating current of about Z-amperes at 20-volts potential was then passed between the two sheets for no more than one second.

The entire operation of light-exposing the photoconductive sheet and electro-exposing the plate requires no more than a fraction of a minute. The resulting plate was then placed upon an ofiice-type lithographic offset press, yield; ing one thousand fully legible reproductions.

Prior to the application of the electromotive force to the plate, the coating was not water-resistant and could be readily removed from the silicate treated surface merely upon wiping with a wet cotton swab. Following application of the electromotive force to the plate (in contact with the exposed photoconductive sheet), the coating in areas corresponding to the image areas of the microfilm negative (and thus corresponding with the conductive areas of the photoconductive sheet) was water-insoluble and firmly bonded and could not be removed by wiping with a wet cloth. In areas corresponding with the background areas of the microfilm, through which no current passed, the coating was readily removed by the dampener rolls on the press. (It could have been wiped away manually before placing the plate on the press.)

The polyvinyl acetate employed in the surface coating of the plate is a tough organophilic film-forming resin. The Benax 2A1 is an anionic surface active agent containing an organophilic portion and an anionic sulfonate moiety, the ratio of carbon atoms to hydrophilic sulfonate groups being 12:1.

It is believed that the anionic moiety of the Benax 2A1 molecule became oriented toward and firmly bonded to the underlying treated metal sheet, these molecules in some way entrapping the polyvinyl acetate resin, although I do not wish to be limited to this hypothesis. The electrophoretically responsive material, i.e. the Benax 2A1 did become oriented however, as appears from the fact that when employed in an identical plate except for the omission of the resin, a highly useful plate resulted which was organophilic and water-insoluble in the image areas, although the press life of such a plate was not as long as that of the plate of the present example.

The following example further illustrates a useful preelectrosensitive plate of the present invention wherein no organophilic resin is employed in conjunction with the electrophoretically responsive and electrophoretically orientable material.

Example II A inch by inch lithographic plate was prepared by coating the silicate-treated aluminum paper laminate described in Example I with a thin film of a solution (about 23%) of sodium oleyl sulfate, marketed as Sipex OS by Alcolac Chemical Corp. The coating Weight on a dry basis was approximately 5 milligrams per square foot.

A photoconductive sheet was exposed through a microfilm line-copy negative, as described in Example I. The exposed photoconductive sheet was then wet with water and pressed or rolled into contact with the coated surface of the aluminum plate. An alternating current of about 2 amperes at volts potential was then applied between the two sheets for about one second. Immediately thereafter the plate was ready for the press, yielding several hundred fully legible copies.

The sodium oleyl sulfate contains an hydrophilic anionic sulfate moiety and an organophilic hydrocarbon tail portion, there being 17 carbon atoms and a single hydrophilic group in the molecule.

The techniques of my invention can be utilized without applying the electrophoretically responsive material as a dry integral component on the hydrophilic surface of the conductive base sheet, as the following example illustrates.

Example III A photoconductive sheet, projection exposed through a line copy microfilm negative, all as described in Example I, was rolled into contact with the silicate treated surface of the aluminum paper laminate described in Example I in the presence of a 1% by weight aqueous solution of phosphated castor oil, having a ratio of carbon atoms (exclusive of those contained in hydrophilic groups) to hydrophilic groups of about 9:1. Approximately one ampere of alternating current at 25-volts potential was then passed for less than one second between the two sheets as the sheets were rolled into contact. At any one time the area to which the current was applied was approximately 12.5 square inches, as dictated by the size of the squeeze rolls. Following application of the electromotive force, the plate was mounted on a lithographic offset press, and yielded 500 fully legible copies, following which the press was shut down.

A photoconductive sheet exposed by projection enlargement through microfilm is only one example of means for obtaining the imagewise conductive cathodic (master) sheet. Various other suitable processes for imagewise exposing photoconductive masters well known in the art include contact exposure, reflective exposure through mirror systems or lens and shutter systems. Moreover, the conductive image sheet containing conductive (image) areas and non-conductive (non-image) areas need not be formed photographically.

In each of the foregoing examples an aluminum-paper laminate having a hydrophilic surface was employed as the base sheet, and it will be apparent that many variations of this sheet construction can be utilized. There is no need for using a paper laminate, where expense is not a consideration. Many other metals, including zinc and magnesium or other conductive materials, can be employed instead of the aluminum. For example, a paper rendered conductive by impregnation with a conductive material can also be utilized.

Hydrophilic surface treatments other than the silicate treatment of aluminum can be utilized, or where desirable (as, for example, where the base exhibits the desired surface character without treatment), can be eliminated. It is generally unnecessary to the formation of an image in accordance with my invention to have a hydrophilic surface present. In fact, so long as it does not prevent passage of current therethrough and does not excessively impede the bond formed by the oriented electrophoretically deposited material, there seems to be no limitation on the particular nature of a surface film or treatment employed on the conductive base. Advantageously, the nature of such layer or treatment otherwise permits versatility in the resulting product. An interesting variation results by employing a sheet of aluminum having an organophilic surface (such as provided by the thin film of mill grease ordinarily found on uncleaned aluminum) as the anode, and a preponderance of a hydrophilic material in conjunction with the electrophoretically responsive material. Upon electro-exposure, a sheet results which is organophilic (ink-receptive) in the areas corresponding with the non-conductive areas of the master, and selectively hydrophilic (water-receptive) in areas correspond ing with the conductive areas of the master.

Likewise, many electrophoretically responsive and electrophoretically orientable organic materials exist having an anionic moiety and an organophilic portion in the molecule and characterized in that they orient to form an organophilic surface on an anodic substrate. Strongly anionic surface active agents having a highly organophilic tail portion, are preferred. Electrophoretically responsive materials found to be useful include carboxylic acids, in which either the carboxyl group is joined directly to hydrophobic groups such as morpholine stearate and triethanolamine oleate, or the carboxyl is joined to organophilic or hydrophobic groups through an intermediate linkage, such as carboxylated polyethoxy derivatives, and disodium N-octadecyl sulfo succinamate. Electrophoretically responsive materials having anionic acid mo'eties other than carboxylic acids can also be used, such as sulfuric esters containing no intermediate group between the anionic moiety and the organophilic portion, e.g. sulfated castor oil, sodium sulfate of Z-ethyl l-hexanol, sodium oleyl sulfate, sodium sulfate derivative of 3,9-diethyl tridecanol-6, sodium cetyl alcohol sulfate, sulfated methyl oleate, sulfated propyl oleate, sodium cetyl sulfate, sodium tallow sulfate; or where the sulfate is joined through an intermediate linkage, as in sulfated glyceryl trioleate or the sodium salt of tridecyl ether sulfate.

Various sulfonates are useful, such as lauryl sulfates and magnesium lauryl sulfate, wherein the acid moiety is attached directly to the oleophilic group, or disodium N-octadecyl sulfo-succinamate, dioctyl ester of sodium sulfosuccinic acid, sodium methyl oleyl taurate, bis tridecyl ester of sodium sulfosuccinate, and oleic acid ester of sodium isethionate, wherein an intermediate linkage is present.

Various alkyl aryl sulfonic acids or their soluble salts can also be used, as exemplified by sodium isopropyl naphalene sulfonate, sodium salt of alkyl aryl sulfonate, decyl benzene sodium sulfonate, dodecyl benzene sodium sulfonate, and amine salt of alkyl aryl sulfonate, wherein no intermediate linkage is present; and sodium salt of alkyl aryl polyether sulfonate and sodium dodecyl diphenyl ether disulfonate, wherein an inter-mediate group links the anionic moiety with the organophilic group. Similar acids and salts of acid groups, such as phosphates and phosphonic acids can be used.

Various ampholytic materials can be employed, such as alkali metal salt of N-coco amino butyric acid, and alkali metal salts such as sodium salt of N-coco B-amino propionate, and the disodium salt of N-tallow B-amino dipropionate. Where the ampholytic materials are employed, appropriate adjustment in the pH of solutions used should be made so that the anionic moiety of the material is dominant.

It will be noted that the above-identified electrophoretically responsive materials contain at least four and generally (and preferably) at least eight carbon atoms (exclusive of carbon atoms in the hydrophilic groups) for each hydrophilic group in the molecule. Furthermore, particularly where the electrophoretically responsive material is employed in solution, as in Example III (that is, where it is not a pre-coated element of the plate) very dilute solutions of the material can be employed. I have made useful plates where the electrophoretically responsive material appeared to exist as what might be termed an anionic contaminant in commercially obtained socalled non ionic surface active agents, notably those of the ester linkage type. The performance of such commercial non-ionic materials, however, has not equaled those of the preferred examples set out hereinabove.

Oleophilic water-insoluble water-dispersible resins, particularly those which form tough films, are preferably employed in conjunction with the electrophoretically responsive materials for best results, exemplified by the polyvinyl acetate of Example I. The utility of these materials does not seem to depend on their specific nature. Among those which have been found to be useful are various silicone resins, alkyd resins, acrylate resins and rubbers, vinyl resins, rubbery polymers such as polyperfluoro butyl amine rubber, various resin or rubbery copolymers exemplified by polyvinylidine chloride-acrylonitrile copolymers.

Ordinarily where a material such as an organophilic resin is incorporated with electrophoretically responsive material in the electro-sensitive material, the relative proportions are not particularly critical. Where the resin is a tough oleophilic film-forming substance, the addition even of small amounts will serve to supplement and strengthen the image. As appears from the specific examples above, I prefer to employ ratios approaching about 1:1 by weight, although either the resin or the electrophoretically responsive material can be predominant in amount. Where a material other than an organophilic material is incorporated in the electrosensitive material, it should be employed in amount such that the desirable characteristics of the resin are exhibited by the image after electro-exposure.

It is to be emphasized that in its broader aspects, my invention is not limited to lithography, but is concerned with the useful application of an image to a conductive substrate through electrophoretic deposition of an electrophoretically responsive material in predetermined areas corresponding to the conductive areas of a cathode sheet having some areas which are also non-conductive. By adjusting current voltages, times, and current densities, so as to control the strength of the bond of the image to the substrate, useful resist coatings can be formed in accordance with the principles hereof. By selection of appropriate polymerizable materials for deposition with the electrophoretically responsive material, indications are that anodic polymerization can occur.

It should also be noted that in the processes hereof direct current ordinarily is unnecessary where the zinc oxide coated sheet of the specific examples is utilized. This sheet appears to serve as a rectifier, and largely to limit current fiow to the proper directioin. Where the conductive master does not exhibit such properties, i.e. iS not a rectifying material, direct current appropriately applied so that the substrate serves as an anode, should be used. Where the rectifying zinc oxide photoconductive sheet of the specific example is used, I prefer to utilize an alternating current.

What I claim is:

1. A pre-electrosensitive printing plate comprising a flexible planar conductive base having a surface, and over and in contact with said surface, and in conductive relation With said base, a coating of electrophoreticallyresponsive and electrophoretically-orientable organic material including discrete mobile molecules, said molecules having an anionic moiety and an organophilic portion, and being further characterized, when subjected to an electromotive force in a conductive medium with the base connected as the anode, in moving and orienting in the areas of current flow to form an organophilic surface with the anionic moiety directed toward the base.

2. A pre-electrosensitive printing plate comprising a flexible planar conductive base having a hydrophilic surface, and over and in contact with said hydrophilic surface, and in conductive relation with said base, a coating of electrophoretically-responsive and electrophoreticallyorientable organic material including discrete mobile molecules, said molecules having an anionic moiety and an organophilic portion and being further characterized, when subjected to an electromotive force in a conductive medium with the base connected as the anode, in moving and orienting in the areas of current flow to form an organophilic surface with the anionic moiety directed toward the base.

3. A pre-electrosensitive printing plate comprising a flexible planar conductive base having a hydrophilic surface, and over and in contact with said hydrophilic surface, and in conductive relation with said base, a coating of electrophoretically-responsive and electrophoreticallyorientable organic material including discrete mobile molecules, said molecules comprising an acid group which includes an oxoand an oxy-oxygen and an organophilic hydrocarbon tail connected to said acid group, and being further characterized, when subjected to an electromotive force in a conductive medium with the base connected as the anode, in moving and orienting in the areas of current flow to form an organophilic surface with the anionic moiety directed toward the base.

4. A pre-electrosensitiveprinting plate comprising a flexible planar conductive base having a hydrophilic surface, and over and in contact with said hydrophilic surface, and in conductive relation with said base, a coating comprising a mixture of a tough film-forming organophilic organic resin and an electrophoretically-responsive and electrophoretically-orientable organic material including discrete mobile molecules, said molecules having an anionic moiety and an organophilic portion and further characterized, when subjected to an electromotive force in a conductive medium with the base connected as the anode, in moving and orienting in the areas of current flow with the anionic moiety directed toward the base and bonding said organophilic resin therewith to said base.

5. A pre-electrosensitive printing plate comprising an aluminum base having a hydrophilic silicate treated surface, and over and in contact with said treated surface, and in conductive relation with said aluminum, a coating of electrophoretically-responsive and electrophoreticallyorientable organic material including discrete mobile molecules, said molecules having an anionic moiety and an organophilic portion and being further characterized, when subjected to an electromotive force in a conductive medium with the base connected as the anode, in moving and orienting in the areas of current flow to form an organophilic surface With the anionic moiety directed toward the base.

6. A method of producing an image on a conductive substrate comprising bringing the conductive substrate, in the presence of moisture and an electrophoreticallyresponsive and electrophoretically-orientable organic material, into contact with a sheet which is electrically conductive only in areas corresponding with said image, and briefly applying an electromotive force across said sheet and said substrate, said substrate being the anode.

7. A method or" producing an ink-receptive image on a conductive substrate comprising bringing said substrate into contact, in the presence of moisture and an electrophoretically-responsive and electrophoretically-orientable organic material, with a master sheet which is electrically conductive only in areas corresponding with said image,

id and briefly applying an electromotive force across said sheet and said substrate, said substrate being the anode, said electrophoretically-responsive material having an anionic moiety and an organophilic portion in the molecule.

8. A method of producing an ink-receptive image on aluminum sheet having an hydrophilic surface comprising exposing a photoconductive master to a light pattern corresponding with said image, thereby rendering said master conductive in the image areas and nonconductive in the background non-image areas, bringing said light-exposed master, in the presence of moisture and an electrophoretically'responsive and electrophoreticallyorientable organic material, into contact with the hydrophilic surface of said aluminum sheet, and briefly applying an electromotive force across said sheet and said substrate, said substrate being the anode.

NORMAN G. TORCHIN, Primary Examiner.

R. E. MARTIN, Assistant Examiner. 

1. A PRE-ELECTROSENSITIVE PRINTING PLATE COMPRISING A FLEXIBEL PLANAR CONDUCTIVE BASE HAVING A SURFACE, AND OVER AND IN CONTACT WITH SAID SURFACE, AND IN CONDUCTIVE RELATION WITH SAID BASE, A COATING OF ELECTROPHORETICALLYRESPONSIVE AND ELECTROPHORETICALLY-ORIENTABLE ORGANIC MATERIAL INCLUDING DISCRETE MOBILE MOLECULES, SAID MOLECULES HAVING AN ANIONIC MOIETY AND AN ORGANOPHILIC PORTION, AND BEING FURTHER CHARACTERIZED, WHEN SUBJECTED TO AN ELECTROMOTIVE FORCE IN A CONDUCTIVE MEDIUM WITH THE BASE CONNECTED AS THE ANODE, IN MOVING AND ORIENTING IN THE AREAS OF CURRENT FLOW TO FORM AN ORGANOPHILIC SURFACE WITH THE SNIONIC MOIETY DIRECTED TOWARD THE BASE. 